For the safety of personnel in various public and commercial structures a relatively large number of strategically placed exits are required which afford the opportunity for quick exit without keys. In most cases it is impractical to provide a security guard at each such exit and accordingly, special locking and release hardware has been evolved. Such mechanism often includes an alarm which will sound either locally or remotely, or both, to indicate that the door has been opened by unauthorized personnel. It is generally required that such hardware provide that a locked door will automatically become unlocked when pressed in the correct location, this normally being done through the agency of a panic bar coupled to the latchbolt. Because a panic bar can also be used surreptitiously in situations not involving emergencies, it is required that an alarm sound under most conditions under which the door is opened by the panic bar. On the other hand, it is required in order to prevent indiscriminate sounding of the alarm in situations not involving emergencies or unauthorized, surreptitious use that authorized personnel exit or enter or both without sounding the alarm. The selection of modes of operation to suit such variety of requirements cannot normally be accomplished without introducing complexity to the mechanism which typically affects its reliability or without making it so difficult to change the modes of operation that it cannot be achieved other than by a highly trained mechanic.
The present invention has for its principal objects therefore to provide a highly reliable, rugged but nevertheless simplified device which can effect exit and entry control of the door to provide a variety of operating modes which can be readily selected without dismantling the unit and without the requirement for special tools other than coded keys.
It is a further object of the invention to provide an exit and entry control lock with audible or other alarm mechanism associated therewith which can be set to operate in as many as four modes both including and excluding the alarm.
In accordance with the invention, there is provided within an armored housing a basic latchbolt mechanism which is dead latched at all times against picking or forcing and in which the dead latch means is at all times coupled to a primary exit release mechanism, such as a panic bar, and which further includes controls to actuate an audible or other alarm device which can be incorporated in the same armored housing. Key operated locks can be provided both from the outside and inside of the door coupled into the latchbolt mechanism so that it can if desired be released without sounding the alarm. A mode selection control is included under which key actuation can be selectively used to disarm the alarm and provide entry. Interacting cam mechanism within the unit can be set so that a key can be used by authorized personnel for entering and exiting with an alarm sounding if a key is not used when leaving. A further actuation of the cam mechanism prevents entry even though a key might be introduced into the outside key cylinder. Also, a key used internally can disarm the alarm for a period of time sufficient for one person to leave. Free passage can be provided for permitting entering and leaving without the use of a key.